/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.datayoo.moql.operand.function;

import org.datayoo.moql.EntityMap;
import org.datayoo.moql.Operand;
import org.datayoo.moql.util.StringFormater;

import java.util.List;

/**
 * 
 * @author Tang Tadin
 *
 */
public class Joint extends AggregationFunction {

	public static final String FUNCTION_NAME = "joint";

	protected Operand operand;

	protected String separator;

	protected StringBuffer sbuf;

	public Joint(List<Operand> parameters) {
		super(FUNCTION_NAME, VARIANT_PARAMETERS, parameters);
		// TODO Auto-generated constructor stub
		if (this.parameters.size() > 2)
			throw new IllegalArgumentException(StringFormater.format(
					"Function '{}' need 1 or 2 parameters!", name));
		operand = parameters.get(0);
		if (parameters.size() == 2) {
			separator = (String)parameters.get(1).operate(null);
		}
	}

	@Override
	public void increment(EntityMap entityMap) {
		// TODO Auto-generated method stub
		Object obj = operand.operate(entityMap);
		if (obj == null)
			return;
		if (sbuf.length() != 0 && separator != null) {
			sbuf.append(separator);
		}
		sbuf.append(obj.toString());
	}

	@Override
	public Object getValue() {
		// TODO Auto-generated method stub
		return sbuf.toString();
	}

	@Override public void clear() {
		sbuf = new StringBuffer();
	}
}
